The Analytical Core will be responsible for performing and supervising all laboratory analyses required by research Project I, II and III in this proposal. The core will carry out all evaluations of cell proliferation, including labeling studies using [3H]-thymidine of crypt organ and 24-hour outgrowth cultures of rectal mucosa biopsies. It will monitor parameters in polyamine metabolism as indices of cell proliferation and as measures of the effectiveness of inhibitors of polyamine synthesis. The effects of piroxicam will be monitored by assaying endpoints in prostaglandin metabolism, including tissue levels of prostaglandin PGE2, 6-KETO-PGF1alpha and thromboxane B2. The Analytical Core will oversee and coordinate collection and processing of all plasma and tissue samples at the various hospitals participating in this program. It will carry out the actual assays and will relate closely to the Biometry Core (B) to provide data for analysis and reporting. Quality assurance and quality control procedure will be developed by the Analytical Core and be supervised by the Biometry Core (B) for each of the tissue acquisition, processing and analysis procedures included in each of the three clinical projects.